The present invention relates to infusion devices for subcutaneous delivery of a medication or a therapeutic fluid by means of an external infusion system and more particularly to an infusion device having releasably connected means for delivery of the medication or the therapeutic fluid from the external infusion system.
Infusion devices are generally known in the art for delivering a medication or a therapeutic fluid to a subcutaneous site in a patient. Such devices commonly comprise a tubular cannula extending from a housing adapted to receive the desired medication via disconnectable means for suitable connection to further components of the infusion system. The possibility of disconnecting the infusion set from the further parts of the infusion system is provided in order to improve the user comfort. The user is enabled to perform activities which do not allow the presence of a pump or the like, or which are hindered by the presence of a pump or the like. In the disconnected state only a part of the infusion set is worn by the patient. This allows for increased mobility. In order to provide such disconnectable means and still maintain a fluid-tight sealing towards the interior of the housing and the tubular cannula that prevents contamination of the infusion site, such devices are commonly provided with a self-sealing penetrable septum on either the housing or the disconnectable part and a hollow needle on the other part adapted to penetrate the septum. Upon withdrawal of the needle from the septum this provides a fluid-tight sealing towards the interior of the housing. The septum and the needle further provide a fluid-tight sealing between the housing and the connector means when medication or therapeutic fluid is delivered to the patient from the external infusion system. Subcutaneous infusion devices of this generally known type are known from e.g. U.S. Pat. No. 5,522,803 to Teissen-Simony and U.S. Pat. No. 5,545,143 to Fischell.
The manufacture of such device including a septum and a needle is rather cumbersome. Further the use of a septum and a needle may lead to some disadvantages during use of such device, viz. a so-called coring whereby, upon penetration of the septum, the hollow needle may become clogged by material from the septum, which may be harmful to the patient since the medication or the therapeutic fluid cannot be delivered as expected, and the potential danger of unintended needle sticks.
For these reasons there is a need for improvements in the infusion devices of the type mentioned in the foregoing, and particularly with respect to providing an infusion device which is far less cumbersome from a manufacturing point of view and which is not clogged by material from a septum and with respect to a device which does not need a septum and a needle to provide a fluid-tight sealing between housing and connector means in a mutually mounted position for these elements. The infusion device according to the invention remedies the above mentioned disadvantages and provides further advantages which will become apparent from the following description.
The advantages of the present invention are obtained by means of an infusion device comprising:
a base element having a cavity and an entry lumen;
a cannula mounted in and extending from said base element, said cannula having a lumen therethrough, said lumen communicating with the entry lumen through said cavity;
connector means for administering a fluid to said entry lumen;
a closing element mounted on said base element to be rotatable about an axis through said base element and having an aperture, where the aperture in one position of the closing element in relation to the base element is aligned with said entry lumen of said base element and in a further rotated position of the closing element in relation to the base element the closing element covers said entry lumen in said base element.
By means of the base element and the closing element which, upon mutual rotation of the closing element and the base element, enables a covering of the lumen in the hub, the need for a self-sealing septum for shutting off the opening in the infusion device where the medication is delivered has become eliminated. Since there is no longer a need for a septum, a needle on the means for delivering the medication or the therapeutic fluid can also be omitted. This means that the manufacturing process has been significantly simplified and production costs have been decreased. The need for the elements causing the coring has been eliminated, whereby the coring problem has likewise been eliminated. The danger of unintended needle sticks is precluded.
In a preferred embodiment the base element comprises a hub with a top and a bottom and an outer surface extending between said top and said bottom, wherein the cavity is formed within said cavity and said entry lumen extend between said outer surface and said cavity and wherein the closing element has substantially the form of a ring element. Hereby a reliable and easy placing of the connector is obtained.
In a preferred embodiment of the invention the closing element of the infusion set further comprises a flange having an inwardly facing surface directed towards the central axis of said hub and wherein said means for administering fluid to said opening in said flange comprises an outward facing surface directed away from central axis of said hub, said outwardly facing surface matching said inward facing surface of said flange of said closing element upon rotation of said closing element in relation to said base element. Hereby it is possible to releasably lock the connector means for administering the medication or the therapeutic fluid in relation to the base element and the closing element. A corresponding effect could be realised if said connector means is secured in relation to said base element and said flange in the area around the aperture is provided with an increased outer diameter hereby providing a pressure against said connector means upon rotation of said closing element.
In a further convenient embodiment the inwardly facing surface, the outwardly facing surface or both surfaces has/have a curvature urging the connector means for administering medication towards the inner flange of the closing element upon rotation of the closing element in relation to the base element. Hereby it is possible to obtain sufficient sealing between the connecting element of the connector means for administering the medication or the therapeutic fluid and the flange without any further sealing means. This desired effect can be obtained by means of an off-set axis of rotation.
It is however a possibility that further sealing means are provided between the hub and the flange and/or between the flange and the means for delivering medication, in order to prevent leakage between these elements. Such sealing means are preferably O-rings or the like.
In a further preferred embodiment the subcutaneous infusion set further comprises means for releasably interlocking the base element and the closing element in relation to a mutual rotation about said central axis. Hereby it is ensured that the possibility of unintended rotation of the closing element in relation to the base element is eliminated, which could otherwise result in a blocking of the administering of the medication or the therapeutic fluid during use.
In a further preferred embodiment of the subcutaneous infusion set means are provided for preventing rotation of the closing element in relation to the base element when the connector means for administering medication to the aperture in the flange of the closing element is not present. Hereby unintended rotation of the closing element in relation to the base element to a position where the aperture is aligned with the entry lumen is prevented. Such alignment could lead to a contamination of the infusion set interior and the infusion site. Examples of suitable means could include a biasing element forming part of the closing element or a biasing element forming part of the base element which in an unloaded position blocks the rotation of the closing element in relation to the base element.
Preferably means for securing said base element in relation to the skin of a patient are provided in connection with base element. It is, however, possible that such means are provided as one or more separate element(s). The securing means is usually an adhesive layer.
The cannula can be either a rigid cannula or a soft cannula. The rigid cannula is usually a steel cannula although other possibilities exist. The soft cannula is usually a PTFE cannula. It is however possible to employ several other polymer material cannulas having similar characteristics for this purpose.
In case said cannula is a soft cannula, there is a need for a support of this during the insertion. In this connection said cavity extends to the top of said hub and self-sealing means covering said cavity towards said top of said hub are provided. An insertion needle is provided for removable insertion through an opening in said closing element, through said self-sealing means and through said cavity and said lumen of said soft cannula and extending beyond the length of said soft cannula.
The invention further relates to an infusion part for use in a subcutaneous infusion set as defined above, the infusion part comprising:
a base element having a cavity and an entry lumen;
a cannula mounted in and extending from said base element, said cannula having a lumen therethrough, said lumen communicating with the entry lumen through said cavity;
a closing element mounted on said base element to be rotatable about an axis through said base element and having an aperture, where the aperture in one position of the closing element in relation to the base element is aligned with said entry lumen of said base element and in a further rotated position of the closing element in relation to the base element the closing element covers said entry lumen in said base element.
This part may be provided as a separate element for the infusion set reusing the connector.
The infusion part may further comprise the features as set forth above in cinnection with the infusion set.